1. Field of the Invention
The present invention relates to an exposure control system for a single reflex camera for controlling the current supply to each circuit in the camera.
2. Description of the Prior Art
Generally, the automatic exposure control system of a camera with electric shutter consists of many circuits such as a light sensing and processing circuit, a storage circuit, an exposure determining circuit, a shutter actuating circuit, a shutter time control circuit and an indication circuit to which the current is supplied from small cells set inside of the camera, whereby a current supply system for minimizing the power consumption in each circuit is needed in order to prolong the life of the cells.
However, the conventional current supply system is constructed in such a manner that the current is supplied to each circuit by the shutter operation in the self-held state while the internal mechanisms are operated one by one. Then, when the rear plane of the focal plane shutter runs, the self-held state is released in such a manner that the current supply to each circuit is interrupted. Thus, during the operation of the camera, the current continues to be always supplied to each circuit so that the life of cells is very short.
The first purpose of the present invention is to eliminate the above mentioned shortcoming in such a manner that the current supply to each circuit in a camera will be controlled efficiently.
The second purpose of the present invention is to actuate the electric shutter electro-magnetically.
The third purpose of the present invention is to adopt the mean light sensing and the partial light sensing which can be switched over selectively.
The fourth purpose of the present invention will be disclosed in accordance with the explanation of the embodiments below.